class F3 {
    public F3() {
        System.out.println("1.执行F3的任务");
    }
}
class F2 extends F3 {
    public F2() {
        System.out.println("2.调用F2的重载构造方法");
        System.out.println("3.执行F2的任务");
    }
    public F2(String s) {
        System.out.println(s);
    }
}
class F1 extends F2 {
    public F1() {
        System.out.println("4.执行F1的任务");
    }
}
public class ZuoYe2 {
    public static void main(String[] args) {
        new F1();
    }
}
